Recently, electronic keys for a vehicle stored in a portable terminal, such as a mobile phone, have been used for opening or closing a door of the vehicle or for ignition of an engine. Electronic keys allow a vehicle door to be automatically opened or closed or allow an engine to be started, provided that the corresponding identification (ID) codes are matched with each other by transmitting ID code, or the like, to a device mounted in the vehicle and comparing the transmitted ID code with the ID code stored in the vehicle.
In addition, the electronic vehicle keys can be shared in a scheme utilizing a separate server, for example, in order to share the electronic key with an additional user trying to use the vehicle. As a result, server operation and sharer authentication processes are necessarily performed.